The role of complement in inflammation is under investigation. The major effort concerns the role of oxidation and reduction in the activation, consumption, and restoration of the individual components of complement. An investigation of the association of the activation of the terminal components of complement with the repression and stimulation of collagen biosynthesis will be initiated. Studies of biopsies from human and animal inflammatory diseases for the deposition of complement and properdin is underway. An extensive study of the early changes of synovial fluid in new cases of arthritis is underway. The particular changes in C3, C4 and C5 and properdin will be correlated with a large battery of biochemical, histologic, and microbiological changes detected in the synovium and synovial fluid.